JP3918236B2 - Method for producing partially diffusion alloyed steel powder - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、Cuを含有する合金鋼粉の製造方法に係わり、特に、Cuの偏析が少なく、圧縮性が高い、Cuを部分拡散合金化させた合金化鋼粉の製造方法に関する。
【０００２】
【従来の技術】
粉末冶金法によって得られる焼結部品は、材料歩留に優れ、加工費が安価であるため、複雑な形状の部品を低コストで得られる利点がある。
従来、焼結部品は、純鉄粉を主原料にCuやNi、Moなどの金属粉と黒鉛を混合し、成形、焼結して製造していた。
【０００３】
しかし、この方法では、純鉄粉、金属粉および黒鉛それぞれの形状、粒度、比重が異なるため、混合後の、輸送、ホッパへの装入、ホッパからの払い出し、成形処理などの際に、純鉄粉、金属粉および黒鉛それぞれが分離し、成分偏析が発生し、焼結部品の強度や寸法が不均一となる問題があった。
これに対して、Cuを部分拡散合金化させた偏析の少ない部分合金化鋼粉の製造方法に関するものとして、仕上げ還元を行っていない粉末冶金用鉄粉に対し、金属含有率で10〜50重量％となるように、平均粒径が５μm 以下、かつ、比表面積が10m2／g 以上である酸化銅を混合し、還元性雰囲気下、 700℃〜 950℃の温度で加熱還元することにより、金属銅を鉄粉表面に拡散付着させることを特徴とする粉末冶金用鉄基銅複合粉末の製造方法が開示されている（特開平 8-92604号公報）。
【０００４】
この方法によれば、脱炭、還元並びに部分合金化を同時に行うが、酸化銅の粒径が小さく、昇温時の低温領域で酸化銅が還元され銅粉となり、鉄粉粒子内へ銅の拡散が進行しすぎて、圧縮性が低下するという問題があり、さらには、必要となる酸化銅のコストが高いという問題がある。
また、特開平1-290702号公報には、水アトマイズしたままの鉄系粉末に、金属Cu粉と酸化鉄粉とを混合し、還元性雰囲気中で加熱し、鉄系粉末表面に還元されたFeとCuを拡散付着する技術が開示されている。
【０００５】
この方法は、脱炭、還元ならびに部分合金化を同時に行うので低コストであるが、還元鉄粉が気孔を有し、形状が不規則であるため見掛け密度が低く、圧縮性が劣る欠点があった。
【０００６】
【発明が解決しようとする課題】
本発明は、前記した従来技術の問題点を解決し、Cuの偏析が少なく、圧縮性が高い、Cuを部分拡散合金化させた合金化鋼粉を経済的に製造する方法を提供することを目的とする。
【０００７】
【課題を解決するための手段】
本発明者らは、Cuを部分拡散合金化せしめる際の合金鋼粉の圧縮性の低下を抑制し、さらにCuの偏析が少ないCuの部分拡散合金化鋼粉の製造方法について鋭意検討した結果、本発明に至った。
本発明は、Ｏ：0.3 〜0.9wt ％、Ｃ：0.3wt ％未満を含有する水アトマイズしたままの鉄系粉末に、平均粒径が20〜100 μm のCuの金属粉を混合し、得られた混合物を、昇温速度を20〜 150℃／分、熱処理温度を 820〜1000℃とする還元性雰囲気下の熱処理で、前記鉄系粉末の表面にCuを部分拡散合金化せしめることを特徴とする部分拡散合金化鋼粉の製造方法である。
【０００８】
前記本発明においては、前記水アトマイズしたままの鉄系粉末の平均粒径が50〜100 μm であることが好ましい。
【０００９】
【発明の実施の形態】
以下、本発明をさらに詳細に説明する。
本発明においては、原料の鉄系粉末として、Ｏを0.3 〜0.9wt ％、Ｃを0.3wt ％未満含有する水アトマイズしたままの鉄系粉末に、平均粒径が20〜100 μm のCuの金属粉を混合し、得られた混合物を還元性雰囲気下、熱処理でCuを部分拡散合金化する。
【００１０】
本発明において原料として用いる水アトマイズしたままの鉄系粉末粒子の表面は、未還元のため、FeO あるいはFe2O3 などの酸化物で覆われている。このため、還元性雰囲気下での仕上還元は、鉄系粉末粒子のCu粉と接触していない粒子表面から優先的に進み、Cu粉と鉄系粉末粒子との接触面は最後に還元されると考えられる。
【００１１】
したがってこの場合、Cuの鉄系粉末粒子中への拡散は最小限に抑えられ、この結果、Cuの固溶硬化による部分合金化鋼粉の圧縮性の低下を抑制することができる。
さらに、本発明によれば、Cu粉の粒子径を大きくすることにより、鉄系粉末粒子に接するCu粉の接触点の数を減らせるので、Cuの固溶硬化量が少なくなり、得られる合金鋼粉の圧縮性の低下が抑制可能となる。
【００１２】
本発明によれば、以上述べた作用により、アトマイズ鉄粉を還元した場合と同等の良好な圧縮性を有するCuの部分拡散合金化鋼粉を１回の熱処理で得ることができる。
本発明において用いる水アトマイズしたままの鉄系粉末としては、Ｏを 0.3〜 0.9wt％、Ｃを 0.3wt％未満含有する鉄系粉末を用いる。
【００１３】
Ｏの含有量が 0.3wt％未満の場合、熱処理時にCuの鉄系粉末粒子中への拡散が過剰に進行し、Cuの固溶硬化によって、得られる合金鋼粉の圧縮性が低下し、逆に 0.9wt％超えの場合は、仕上げ還元速度が遅く実用的でない。
Ｃの含有量が 0.3wt％以上の場合は、仕上還元後に得られる合金鋼粉の圧縮性が低くなる。
【００１４】
さらに、上記鉄系粉末としては、Ｏを 0.3〜 0.9wt％、Ｃを 0.3wt％未満含有し、不可避的不純物の含有量がSi： 0.2wt％以下、Mn： 0.2wt％以下、Ｐ：0.01wt％以下、Ｓ：0.01wt％以下である鉄粉が好ましい。
また、鉄系粉末の平均粒径は50〜100 μm とするのが好ましい。
鉄系粉末の平均粒径が50μm 未満では、水アトマイズ法ではアトマイズコストが高く実用的でなく、逆に100 μm を超えると、合金鋼粉から製造される焼結体の強度が低下するので好ましくない。
【００１５】
金属Cu粉の添加量は、混合物中の重量％で 0.5〜 15wt ％とするのが好ましい。金属Cu粉の添加量が0.5wt ％未満では、Cu添加による焼結体の強度向上の効果がなく、逆に15wt％を超えると圧縮性が低下するので好ましくない。
金属Cu粉の平均粒径は20〜100 μm とする。
金属Cu粉の平均粒径が20μm 未満の場合には、仕上還元の熱処理中に、鉄系粉末粒子中へのCuの拡散量が増加し、圧縮性が低下する。一方、金属Cu粉の平均粒径が100 μm を超えると、仕上還元の熱処理でのCu粉の鉄系粉末粒子への拡散付着が不十分となり、仕上還元後の輸送、ホッパへの装入、ホッパからの払出し、成形処理等の際にCuの成分偏析が発生する。このため、金属Cu粉の平均粒径を20〜100 μm の範囲に限定した。
【００１６】
なお、前記した平均粒径は、レーザ回折型マイクロトラック粒度分布計で測定した50％粒径で定義される。
前記した鉄粉などの鉄系粉末に合金成分であるCuを部分拡散合金化させる時の熱処理としては、還元性雰囲気下で、好ましくはH2を含むガス中で、 820〜1000℃の温度条件下で行う。
【００１７】
還元時の熱処理温度が 820℃未満の場合、鉄系粉末の脱炭、還元が進まず、圧縮性が低下し、逆に1000℃を超えると合金成分であるCuが鉄系粉末粒子中に拡散しすぎて圧粉密度が低下するので好ましくない。
熱処理時の昇温速度は、20〜 150℃／分とする。
昇温速度が20℃／分未満の場合、合金化鋼粉の特性は影響されないが、生産性が低下し、経済的にも好ましくない。一方、逆に 150℃／分を超えると脱炭が完全には進行せず、圧縮性が低下し好ましくない。
【００１８】
部分拡散合金化鋼粉のＣ、Ｏの含有量は、Ｃ：0.01wt％以下、Ｏ：0.15wt％以下であることが好ましい。これは、部分拡散合金化鋼粉のＣ、Ｏの含有量がこれらの範囲を外れると、圧縮性が低下するためである。
また、実際に使用する場合、本発明鋼粉と市販のアトマイズ純鉄粉や還元鉄粉と混合して用いても何ら問題はない。
【００１９】
【実施例】
以下、本発明を実施例に基づき具体的に説明する。
（実施例１）
表１に示す３種類の未還元の水アトマイズしたままの鉄粉（以下水アトマイズ鉄粉とも記す）に、表１に示す種々の粒径の金属Cu粉２wt％を添加、混合し、得られた混合粉を熱処理炉中で昇温速度50℃／分で昇温し、Ｈ2 雰囲気中、 880℃の条件下、１hr、部分合金化熱処理を行った。得られた熱処理後の混合粉を解砕、分級し、合金鋼粉（本発明例、試験No.1〜No.4および比較例、試験No.5）を得た。
【００２０】
また、表１に示す未還元の水アトマイズしたままの鉄粉を、金属Cu粉無添加で上記と同様の条件下で熱処理し、熱処理後の混合粉を解砕、分級し、鋼粉（比較例、試験No.6）を得た。
一方、表１に示す未還元の水アトマイズしたままの鉄粉を、Ｈ2 雰囲気中、 950℃の条件下、１hr、脱炭、還元し、さらに得られた鉄粉に、Cu2O粉を、Cu換算で２wt％添加、混合した後、熱処理温度を 850℃とした以外は前記した本発明例１と同一の脱炭、還元条件で部分合金化熱処理を行った（従来例：２回還元法、試験No.7）。
【００２１】
次に、上記した条件で製造した合金鋼粉および鋼粉について圧縮性を測定、評価し、また合金鋼粉および鋼粉のＣ、Ｏの分析を行った。
得られた結果を表１に示す。
なお、圧縮性の測定、評価は、合金鋼粉または鋼粉にステアリン酸亜鉛を１wt％混合した後、７t/cm2 の成形圧で直径が11mm、高さが10mmの成形体を作製し、その密度を求めることにより行った。
【００２２】
本発明例の試験No.1〜No.4は、水アトマイズのまま鉄粉を還元した場合（比較例、試験No.6）とほぼ同等の圧縮性を有していることが分かる。また、本発明例の試験No.1〜No.4と比較例の試験No.6とを比較すると、金属Cu粉の粒径が20μm 未満では圧縮性が低下することがわかる。
また、本発明によれば、水アトマイズのまま鉄粉を還元した後、Cu2O粉を添加、混合し、得られた混合粉を還元性雰囲気下で熱処理する方法、すなわち、従来の２回還元法、による鋼粉より、優れた圧縮性を有する鋼粉が得られることが分かった。
【００２３】
【表１】
（実施例２）
実施例１の試験No.4と同じ、平均粒径65μm 、Ｏ量0.65wt％、Ｃ量0.21wt％の水アトマイズのままの鉄粉に、平均粒径45μm のアトマイズ銅粉を２wt％添加混合して、昇温速度、還元時の熱処理温度を表２に示す各種条件に設定し熱処理を行い、得られた合金鋼粉の圧縮性を実施例１と同様の方法で測定、評価し、また合金鋼粉のＣ、Ｏの分析を行った。
【００２５】
得られた結果を、熱処理条件と併せて表２に示す。
表２に示されるように、本発明例の試験No.8〜No.12 は、比較例の試験No.13 〜No.15 に比較して、高圧縮性の部分拡散合金化鋼粉となっていることが分かる。熱処理時の最高温度が820 ℃未満の場合（試験No.13 ）、1000℃を超えた場合（試験No.14 ）、昇温速度が150 ℃／分を超えた場合（試験No.15 ）は、いずれの場合も合金鋼粉の圧縮性が低下している。
【００２６】
【表２】
（実施例３）
表３に示す平均粒径が75μm の未還元の水アトマイズしたままの鉄粉に、平均粒径が35、60、80、100 μm の電解銅粉を各２wt％添加、混合し、得られた混合粉を熱処理炉中で昇温速度80℃／分で昇温し、Ｈ2 雰囲気中、熱処理温度が880 ℃の条件下、１hr、部分合金化熱処理を行い、熱処理後の混合粉を解砕、分級し、合金鋼粉（本発明例、試験No.16 〜No.19 ）を各１ton 製造した。
【００２８】
また、比較例として、平均粒径が150 μm の電解銅粉を使用した以外は上記本発明例と同様の方法で合金鋼粉（比較例、試験No.20 ）を１ton 製造した。
さらに、比較例として、Cu粉無添加とした以外は上記本発明例と同様の方法で鋼粉を製造し、得られた鋼粉に平均粒径が30μm の電解銅粉を単純混合し１ton の鋼粉（比較例、試験No.21 ）を製造した。
【００２９】
得られた合金鋼粉および鋼粉を、各々別個に、チューブ式搬送機（型式：TSO5-7AB、日本興産社製）を用いて25kg／分の速度で搬送し、25kg毎に、搬送機から合金鋼粉または鋼粉を採取し、得られた試料のCuの分析値の標準偏差（１σ）によりCuの偏析の程度を評価し、その結果を表３に示す。
【００３０】
【表３】
表３から、本発明例の合金鋼粉（試験No.16 〜No.19 ）では、σ＝0.02〜0.05％であるのに対し、比較例の試験No.20 の合金鋼粉では、σ＝0.15％、比較例の試験No.21 の単純混合粉の鋼粉では、σ＝0.20％であり、本発明によれば、銅の偏析が大幅に防止できることが分かった。
（実施例４）
表４に示す平均粒径が75μm の未還元の水アトマイズしたままの鉄粉に、平均粒径が45μm のアトマイズ銅粉を５wt％、または10wt％添加、混合し、得られた混合粉を熱処理炉中で昇温速度80℃／分で昇温し、Ｈ2 雰囲気中、熱処理温度が880 ℃の条件下、１hr、部分合金化熱処理を行い、熱処理後の混合粉を解砕、分級し、合金鋼粉（本発明例、試験No.22 、No.23 ）を各１ton 製造した。さらに、これら合金鋼粉に、市販の純鉄粉（川崎製鉄製 KIP 301A ）を表４に示す配合量で配合し、混合して１ton の鉄粉とした。なお、これら鉄粉のCu含有量は２wt％と同一である。
【００３２】
得られたこれら鉄粉を、実施例３と同様に、各々別個に、チューブ式搬送機（型式：TSO5-7AB、日本興産社製）を用いて25kg／分の速度で搬送し、25kg毎に、搬送機から鉄粉を採取し、得られた試料のCuの分析値の標準偏差（１σ）によりCuの偏析の程度を評価し、その結果を表４に示す。
【００３３】
【表４】
表４から、本発明例の鉄粉（試験No.22 ）ではσ＝0.02％、本発明例の鉄粉（試験No.23 ）ではσ＝0.03％であった。本発明例の鉄粉は、比較例の試験No.20 の合金鋼粉（σ＝0.15％）、比較例の試験No.21 の単純混合粉の鋼粉（σ＝0.20％）に比べ、銅の偏析が大幅に防止できることが分かった。
【００３５】
【発明の効果】
本発明によれば、圧縮性が高く、Cuの偏析が少ない合金化鋼粉を経済性に優れた方法で製造することが可能となり、その工業的価値は大きい。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing Cu-containing alloy steel powder, and more particularly, to a method for producing alloyed steel powder in which Cu is partially diffused and has low segregation of Cu and high compressibility.
[0002]
[Prior art]
Sintered parts obtained by powder metallurgy have the advantage of being able to obtain parts with complex shapes at low cost because they have excellent material yield and low processing costs.
Conventionally, sintered parts have been manufactured by mixing pure iron powder as a main raw material with metal powder such as Cu, Ni, Mo and graphite, and molding and sintering.
[0003]
However, in this method, pure iron powder, metal powder, and graphite have different shapes, particle sizes, and specific gravities. Therefore, after mixing, pure iron powder, metal powder, and graphite have a pure content during transportation, charging into the hopper, dispensing from the hopper, molding processing, etc. Each of iron powder, metal powder, and graphite was separated, component segregation occurred, and the strength and dimensions of the sintered parts were not uniform.
On the other hand, as a method for producing a partially alloyed steel powder with a low segregation obtained by forming a partial diffusion alloy of Cu, 10-50 wt.% In terms of metal content with respect to iron powder for powder metallurgy not subjected to final reduction. % By mixing copper oxide having an average particle size of 5 μm or less and a specific surface area of 10 m 2 / g or more, and heating and reducing at a temperature of 700 ° C. to 950 ° C. in a reducing atmosphere, A method for producing an iron-based copper composite powder for powder metallurgy, characterized in that metallic copper is diffused and adhered to the surface of iron powder (Japanese Patent Laid-Open No. 8-92604) is disclosed.
[0004]
According to this method, decarburization, reduction, and partial alloying are simultaneously performed. However, the particle size of copper oxide is small, and copper oxide is reduced to a copper powder in a low temperature region at the time of temperature rise. There is a problem in that the diffusion proceeds too much and the compressibility is lowered, and further, there is a problem that the cost of the required copper oxide is high.
In addition, in Japanese Patent Laid-Open No. 1-290702, a metal Cu powder and an iron oxide powder are mixed with an iron-based powder that has been atomized in water, heated in a reducing atmosphere, and reduced to the surface of the iron-based powder. A technique for diffusion deposition of Fe and Cu is disclosed.
[0005]
This method is low cost because decarburization, reduction, and partial alloying are simultaneously performed, but the reduced iron powder has pores and has an irregular shape, resulting in low apparent density and poor compressibility. It was.
[0006]
[Problems to be solved by the invention]
The present invention solves the problems of the prior art described above, and provides a method for economically producing alloyed steel powder in which Cu is partly diffusion alloyed, with low segregation of Cu and high compressibility. Objective.
[0007]
[Means for Solving the Problems]
The inventors of the present invention, as a result of diligently studying a method for producing a partially diffused alloyed steel powder of Cu, which suppresses a decrease in compressibility of the alloyed steel powder when Cu is partially diffused alloyed, and has less segregation of Cu, The present invention has been reached.
The present invention is obtained by mixing Cu metal powder having an average particle size of 20 to 100 μm with water-based iron-based powder containing O: 0.3 to 0.9 wt% and C: less than 0.3 wt%. Characterized in that Cu is partially diffusion alloyed on the surface of the iron-based powder by heat treatment in a reducing atmosphere at a heating rate of 20 to 150 ° C./min and a heat treatment temperature of 820 to 1000 ° C. It is a manufacturing method of the partial diffusion alloying steel powder to do.
[0008]
In the present invention, it is preferable that an average particle diameter of the water-based iron-based powder is 50 to 100 μm.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
In the present invention, as an iron-based powder as a raw material, Cu metal having an average particle size of 20 to 100 μm is added to a water-based iron-based powder containing 0.3 to 0.9 wt% of O and less than 0.3 wt% of C. The powder is mixed, and the resulting mixture is heat-treated in a reducing atmosphere to form a partial diffusion alloy of Cu.
[0010]
The surface of the water-based iron-based powder particles used as a raw material in the present invention is covered with an oxide such as FeO or Fe 2 O 3 because it is not reduced. For this reason, the finish reduction in a reducing atmosphere preferentially proceeds from the particle surface not in contact with the Cu powder of the iron-based powder particles, and the contact surface between the Cu powder and the iron-based powder particles is finally reduced. it is conceivable that.
[0011]
Therefore, in this case, the diffusion of Cu into the iron-based powder particles is minimized, and as a result, it is possible to suppress a decrease in compressibility of the partially alloyed steel powder due to solid solution hardening of Cu.
Furthermore, according to the present invention, by increasing the particle diameter of the Cu powder, the number of contact points of the Cu powder in contact with the iron-based powder particles can be reduced. A decrease in compressibility of the steel powder can be suppressed.
[0012]
According to the present invention, by the action described above, Cu partially diffusion alloyed steel powder having good compressibility equivalent to that obtained by reducing atomized iron powder can be obtained by one heat treatment.
As the iron atomized powder used in the present invention, the iron atom powder containing 0.3 to 0.9 wt% of O and less than 0.3 wt% of C is used.
[0013]
When the O content is less than 0.3 wt%, Cu diffuses excessively into the iron-based powder particles during heat treatment, and the solid solution hardening of Cu decreases the compressibility of the resulting alloy steel powder, and conversely If it exceeds 0.9 wt%, the finishing reduction rate is slow and impractical.
When the content of C is 0.3 wt% or more, the compressibility of the alloy steel powder obtained after finish reduction becomes low.
[0014]
Further, the iron-based powder contains 0.3 to 0.9 wt% of O and less than 0.3 wt% of C, the content of inevitable impurities is Si: 0.2 wt% or less, Mn: 0.2 wt% or less, P: 0.01 Iron powder that is wt% or less and S: 0.01 wt% or less is preferable.
The average particle size of the iron-based powder is preferably 50 to 100 μm.
If the average particle size of the iron-based powder is less than 50 μm, the atomization cost is high and impractical with the water atomization method.On the other hand, if it exceeds 100 μm, the strength of the sintered body produced from the alloy steel powder is reduced, which is preferable. Absent.
[0015]
The amount of metal Cu powder added is preferably 0.5 to 15 wt% in terms of weight% in the mixture. If the added amount of metallic Cu powder is less than 0.5 wt%, the effect of improving the strength of the sintered body due to the addition of Cu is not effective.
The average particle size of the metal Cu powder is 20-100 μm.
When the average particle diameter of the metal Cu powder is less than 20 μm, the amount of Cu diffusion into the iron-based powder particles increases during the heat treatment for finish reduction, and the compressibility decreases. On the other hand, when the average particle size of the metal Cu powder exceeds 100 μm, the diffusion and adhesion of Cu powder to the iron-based powder particles in the heat treatment for finish reduction becomes insufficient, and transport after finish reduction, charging into the hopper, Cu component segregation occurs during hopper payout and molding. For this reason, the average particle diameter of metal Cu powder was limited to the range of 20-100 micrometers.
[0016]
The average particle diameter is defined as a 50% particle diameter measured with a laser diffraction type microtrack particle size distribution meter.
As a heat treatment when the alloy component Cu is partially diffusion alloyed with the iron-based powder such as iron powder as described above, a temperature condition of 820 to 1000 ° C. in a reducing atmosphere, preferably in a gas containing H 2 is preferable. Do it below.
[0017]
If the heat treatment temperature during reduction is less than 820 ° C, the decarburization and reduction of the iron-based powder will not proceed and the compressibility will decrease. Conversely, if it exceeds 1000 ° C, the alloy component Cu will diffuse into the iron-based powder particles. This is not preferable because the powder density is reduced too much.
The heating rate during heat treatment is 20 to 150 ° C./min.
When the rate of temperature increase is less than 20 ° C./min, the characteristics of the alloyed steel powder are not affected, but the productivity is lowered and this is not economically preferable. On the other hand, if it exceeds 150 ° C./min, decarburization does not proceed completely, and the compressibility is lowered, which is not preferable.
[0018]
The C and O contents of the partially diffusion alloyed steel powder are preferably C: 0.01 wt% or less and O: 0.15 wt% or less. This is because if the content of C and O in the partially diffusion alloyed steel powder is out of these ranges, the compressibility is lowered.
In actual use, there is no problem even if the steel powder of the present invention is mixed with commercially available atomized pure iron powder or reduced iron powder.
[0019]
【Example】
Hereinafter, the present invention will be specifically described based on examples.
Example 1
It is obtained by adding and mixing 2 wt% of metal Cu powder having various particle sizes shown in Table 1 to the three types of unreduced water atomized iron powder shown in Table 1 (hereinafter also referred to as water atomized iron powder). The mixed powder was heated in a heat treatment furnace at a heating rate of 50 ° C./min, and partially alloyed for 1 hour in an H 2 atmosphere at 880 ° C. The obtained mixed powder after the heat treatment was pulverized and classified to obtain alloy steel powders (Examples of the present invention, Test Nos. 1 to 4 and Comparative Examples, Test No. 5).
[0020]
In addition, unreduced water atomized iron powder shown in Table 1 is heat treated under the same conditions as above without adding metal Cu powder, and the mixed powder after heat treatment is crushed and classified, and steel powder (comparison) Example, test No. 6) was obtained.
On the other hand, the unreduced water atomized iron powder shown in Table 1 was decarburized and reduced in a H 2 atmosphere at 950 ° C. for 1 hour, and Cu 2 O powder was added to the obtained iron powder. Then, after adding and mixing 2 wt% in terms of Cu, a partial alloying heat treatment was performed under the same decarburization and reduction conditions as in the above-described Invention Example 1 except that the heat treatment temperature was set to 850 ° C (conventional example: twice reduction) Law, Test No. 7).
[0021]
Next, compressibility was measured and evaluated for the alloy steel powder and steel powder produced under the above-described conditions, and C and O analysis of the alloy steel powder and steel powder were performed.
The obtained results are shown in Table 1.
The measurement of the compressibility, evaluation after mixing 1 wt% of zinc stearate alloy steel powder or steel powder, 7t / cm 2 of 11mm in diameter at a molding pressure, height and form a compact of 10 mm, This was done by determining the density.
[0022]
It can be seen that Test Nos. 1 to No. 4 of the present invention examples have substantially the same compressibility as when the iron powder was reduced with water atomization (Comparative Example, Test No. 6). Further, comparing the test No. 1 to No. 4 of the present invention example with the test No. 6 of the comparative example, it can be seen that the compressibility is lowered when the particle size of the metal Cu powder is less than 20 μm.
Further, according to the present invention, after reducing iron powder with water atomization, Cu 2 O powder is added and mixed, and the resulting mixed powder is heat-treated in a reducing atmosphere, that is, the conventional two times. It turned out that the steel powder which has the outstanding compressibility is obtained from the steel powder by a reduction method.
[0023]
[Table 1]
(Example 2)
Same as Test No. 4 in Example 1, 2 wt% of atomized copper powder with an average particle size of 45 μm added to iron powder with an average particle size of 65 μm, O content of 0.65 wt% and C content of 0.21 wt%. Then, the heating rate was set at various conditions shown in Table 2 for the rate of temperature rise and the heat treatment temperature during reduction, and the compressibility of the obtained alloy steel powder was measured and evaluated in the same manner as in Example 1. The alloy steel powder was analyzed for C and O.
[0025]
The obtained results are shown in Table 2 together with the heat treatment conditions.
As shown in Table 2, the test Nos. 8 to 12 of the present invention example are highly compressible partially diffused alloyed steel powders compared to the test Nos. 13 to 15 of the comparative examples. I understand that When the maximum temperature during heat treatment is less than 820 ° C (test No. 13), when it exceeds 1000 ° C (test No. 14), and when the rate of temperature rise exceeds 150 ° C / min (test No. 15) In either case, the compressibility of the alloy steel powder is reduced.
[0026]
[Table 2]
(Example 3)
Obtained by adding and mixing 2 wt% each of electrolytic copper powder with average particle diameters of 35, 60, 80, and 100 μm into unreduced water atomized iron powder with average particle diameter of 75 μm shown in Table 3 The mixed powder is heated in a heat treatment furnace at a heating rate of 80 ° C./min. In a H 2 atmosphere, the heat treatment temperature is 880 ° C., and is subjected to partial alloying heat treatment for 1 hour, and the mixed powder after the heat treatment is crushed. 1 ton each of alloy steel powders (Examples of the present invention, tests No. 16 to No. 19) were manufactured.
[0028]
Further, as a comparative example, 1 ton of alloy steel powder (comparative example, test No. 20) was produced in the same manner as in the above-described example of the present invention except that electrolytic copper powder having an average particle size of 150 μm was used.
Furthermore, as a comparative example, steel powder was produced by the same method as the above-mentioned present invention except that no Cu powder was added, and the obtained steel powder was simply mixed with electrolytic copper powder having an average particle size of 30 μm to 1 ton. Steel powder (comparative example, test No. 21) was produced.
[0029]
The obtained alloy steel powder and steel powder are separately transported at a rate of 25 kg / min using a tube-type transporter (model: TSO5-7AB, manufactured by Nippon Kosan Co., Ltd.), and every 25 kg from the transporter. Alloy steel powder or steel powder was sampled, and the degree of segregation of Cu was evaluated by the standard deviation (1σ) of the Cu analysis value of the obtained sample. The results are shown in Table 3.
[0030]
[Table 3]
From Table 3, σ = 0.02 to 0.05% for the alloy steel powders of the present invention examples (test No. 16 to No. 19), whereas for the alloy steel powder of the test example No. 20 of the comparative example, σ = In the steel powder of the simple mixed powder of 0.15% and test No. 21 of the comparative example, σ = 0.20%, and according to the present invention, it was found that the segregation of copper can be largely prevented.
Example 4
Add 5 wt% or 10 wt% of atomized copper powder with an average particle size of 45 μm to unreduced water atomized iron powder with an average particle size of 75 μm as shown in Table 4 and mix, and heat-treat the resulting mixed powder In the furnace, the temperature was raised at a rate of 80 ° C./min. In the H 2 atmosphere, the heat treatment temperature was 880 ° C., 1 hour, partially alloyed heat treatment was performed, and the mixed powder after the heat treatment was crushed and classified. Alloy steel powders (Examples of the present invention, Test No. 22, No. 23) were produced in 1 ton each. Furthermore, commercially available pure iron powder (KIP 301A made by Kawasaki Steel) was blended with these alloy steel powders in the blending amounts shown in Table 4, and mixed to obtain 1 ton iron powder. In addition, Cu content of these iron powders is the same as 2 wt%.
[0032]
In the same manner as in Example 3, the obtained iron powders were separately transported at a rate of 25 kg / min using a tube-type transporter (model: TSO5-7AB, manufactured by Nippon Kosan Co., Ltd.), and every 25 kg. The iron powder was collected from the conveyor, and the degree of segregation of Cu was evaluated by the standard deviation (1σ) of the analysis value of Cu of the obtained sample. The results are shown in Table 4.
[0033]
[Table 4]
From Table 4, σ = 0.02% for the iron powder of the present invention example (Test No. 22), and σ = 0.03% for the iron powder of the present invention example (Test No. 23). The iron powder of the present invention example is copper alloy steel powder (σ = 0.15%) of the test No. 20 of the comparative example and the steel powder of the simple mixed powder of the test No. 21 of the comparative example (σ = 0.20%). It has been found that segregation of can be largely prevented.
[0035]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to manufacture the alloyed steel powder with high compressibility and few segregation of Cu by the method excellent in economical efficiency, The industrial value is large.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18505497A JP3918236B2 (en) | 1996-08-02 | 1997-07-10 | Method for producing partially diffusion alloyed steel powder |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8-204657 | 1996-08-02 | ||
| JP20465796 | 1996-08-02 | ||
| JP18505497A JP3918236B2 (en) | 1996-08-02 | 1997-07-10 | Method for producing partially diffusion alloyed steel powder |
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| JP3918236B2 true JP3918236B2 (en) | 2007-05-23 |
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| WO2017162499A1 (en) | 2016-03-23 | 2017-09-28 | Höganäs Ab (Publ) | Iron based powder |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2009010445A2 (en) * | 2007-07-17 | 2009-01-22 | Höganäs Ab (Publ) | Iron-based powder combination |
| JP5442145B1 (en) | 2012-10-24 | 2014-03-12 | Ｎｔｎ株式会社 | Sintered bearing |
| KR101531347B1 (en) * | 2012-12-24 | 2015-06-25 | 주식회사 포스코 | Method for manufacturing iron-based diffusion bonding powders |
| KR101531346B1 (en) * | 2012-12-24 | 2015-06-25 | 주식회사 포스코 | Method for manufacturing diffusion bonding iron-based powders |
| US10774403B2 (en) * | 2014-12-12 | 2020-09-15 | Jfe Steel Corporation | Iron-based alloy powder for powder metallurgy, and sinter-forged member |
| CN104858444B (en) * | 2015-06-11 | 2017-04-26 | 四川理工学院 | Hypoxic manganese-containing water atomized steel powder reduction process |
| CN111761051B (en) * | 2020-06-10 | 2022-07-19 | 鞍钢(鞍山)冶金粉材有限公司 | Copper-containing iron powder for powder metallurgy and preparation method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2017162499A1 (en) | 2016-03-23 | 2017-09-28 | Höganäs Ab (Publ) | Iron based powder |
| US11685979B2 (en) | 2016-03-23 | 2023-06-27 | Höganäs Ab (Publ) | Iron based powder |
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